In the prior art, it is known to use FADE OUT or FADE IN signals (collectively referred to as a FADE signal) in order to execute a fading out of a particular audio signal or the fading in of such a signal. FIG. 1 depicts the general shape of such signals. It is also known that FADE signals can be generated by an editor used in conjunction with an audio mixer.
However, when an editor is used to generate a FADE signal, typically a fade can be implemented only to either the minimum or maximum level of the FADE signal such as shown in FIG. 1. In order to overcome this drawback, it is known to provide one or more faders on the audio mixing console in order to adjust the maximum and/or minimum level of the FADE signal. For example, as shown in FIG. 2, a main fader may be used to lower the maximum FADE level or FADE IN point. A secondary fader can be used to adjust the minimum fade level or FADE OUT point thereby providing a depth of fade control.
However, in some circumstances a drawback exists with this two control scheme. That is, the two controls are interactive. This occurs on the Soundcraft 200 BVE and the Sony MXP-2900, for example. To further explain, the "interactive" nature of these controls means that when the main fader is adjusted to change the maximum fade level, the minimum fade level is also adjusted even if the secondary fader is not adjusted. This may occur if, for example, the minimum level is determined to be some ratio of the maximum level. This occurs in the Soundcraft 200 BVE, for example, because the main fader is located in the audio path. Therefore, if the main fader is adjusted, the level of attenuation due to the secondary fader is also effected. In effect, the main fader shifts the entire FADE signal curve. To illustrate this, reference is made to FIGS. 3A-3B.
From FIGS. 3A-3B, it can be seen that if, for example, the main fader is set at a position corresponding to a maximum value (MAX) and the secondary fader is set at point A (an arbitrary reference point), then the FADE signal will resemble that shown by solid lines in FIG. 3A. If the main fader is adjusted as shown in FIG. 3B, and the secondary fader is not adjusted (it remains at reference point A), then the FADE signal will resemble that shown by the solid lines in FIG. 3B. In other words, adjusting the main fader downwards causes a downward shift of the entire signal including the FADE OUT level. This can be undesirable in that it may necessitate adjusting the secondary fader, if, for example, an absolute FADE OUT level is desired. That is, if it is desired that the FADE OUT level not be a ratio of the main fader or maximum level.
While a FADE OUT signal is shown in FIGS. 2-3, it will be readily apparent to one of ordinary skill in the art that the same phenomena will occur with a FADE IN signal such as shown in FIG. 1. To avoid unnecessary duplication and for clarity, the following will discuss either a FADE OUT signal or generally a FADE signal. It is to be understood that the invention clearly applies to both FADE IN and FADE OUT signals.